Compression bone staple, apparatus and method of the invention

ABSTRACT

A method and apparatus for interosseous bone fixation uses a compression staple, generally U-shaped, having a pair of legs with sharp front ends and proximal ends interconnect by a bridge portion that is resilient and bowed, the staple having an initial configuration and capable of a tensioned configuration by spreading apart the legs by a certain amount causing the curvature of the bowed bridge to lessen and the legs urged towards each other with certain compressive spring force. A staple applicator supports and guides the staple and positions the tensioned staple with its pointed ends forward, adjacent an ejection port at the front of the applicator. A powered strike member is mounted for longitudinal movement and has a front end that will strike the rear of the tensioned staple with percussive force and eject it in tensioned configuration from the applicator.

CROSS-REFERENCE

This application is a continuation application of U.S. Ser. No.10/896,360, filed Jul. 20, 2004, which is a continuation application ofU.S. Ser. No. 09/985,719, filed Nov. 6, 2001, now U.S. Pat. No.6,783,531, issued Aug. 31, 2004, which is a continuation application ofU.S. Ser. No. 09/500,060, filed Feb. 8, 2000, now U.S. Pat. No.6,348,054, issued Feb. 19, 2002, which is a continuation-in-partapplication of U.S. Ser. No. 09/299,285, filed Apr. 26, 1999, now U.S.Pat. No. 6,059,787, issued May 9, 2000, which are incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to devices and techniques for securingbone segments across a fracture site, and more particularly relates to abone stapling method and apparatus for achieving compression betweensegments.

2. Description of the Prior Art

In treating a bone fracture it is common practice to fasten one bonesegment to the other so as to stabilize and immobilize them for theduration of the bone consolidation process. Thus there is the techniqueof internal fixation or direct mechanical fastening of the bonesegments.

Traditionally, fixation has been accomplished by variety of apparatusand techniques, the more common involving the use of metallic fasteningdevices such as screws, connector plates (secured to the bone byscrews), pins and clips. These methods invariably involve the drillingof screw holes in the bone and the use of related equipment such asdrill hole templates.

Conventional U-shaped clips have also been used, the clip legs beinginstalled one each in holes in the opposing bone segments. The rigidstructure of such clips, like the other fixation devices mentionedabove, provide rigid immobilization of the fracture zone. Such devicesalso served to maintain the distance between segments, which was foundhowever, among other things, to hinder compression induced bycontractions of skeletal muscles in some cases, and prevent theestablishment of compressive force between the bone segments which isfavorable to bone consolidation or knitting. In this regard the conceptof creating dynamic compressive force across an osteotomy or bonefracture site has become well recognized as a technique to promoteprimary bone healing, i.e. consolidation that is faster and of betterquality.

Thus there has evolved a number of fastening devices such as clips andthe like, designed to deliver compression. Accordingly in U.S. Pat. No.3,939,294 there is provided a clasp or clip of spring material having apair of spaced-apart, inwardly inclined legs connected by a Z-shapedupper portion. Sloped holes are drilled in adjoining bone segments andtools are used to manipulate and install one leg, and then the other legis pulled toward the other hole , spreading the Z-shaped elasticportion, and then inserted in the other hole. Unfortunately this methodrequires the drilling of specially sloped holes, involves multiple stepsand is time-consuming, and like the conventional rigid fasteningtechniques, requires relatively large surgical opening. Also, the manualinstallation of the clip using hemostats and the like is difficult,requires meticulous skill and handling.

In U.S. Pat. No. 4,838,254 the legs of a pair of metallic clips are,inserted in pairs of specially angled bores in respective opposing bonesegments. The exposed tops of the two installed clips then serve asfastening heads for a spring that is connected between the clips.

In U.S. Pat. No. 4,841,960 the disclosed “compression” clip isessentially a clip with opposing legs that are installed in pre-drilledholes and features a crimpable web that joins the top ends of the legs.A crimping tool is used to crimp the web in an effort to set upcompression between the embedded legs.

U.S. Pat. No. 4,852,558 also requires manual installation of separatelegs in pre-drilled holes, the tops of the install legs then beinginterconnected with a ratchet mechanism which must be operated to drawthe legs together. This design appears inherently limited regardingadjustability and maintenance of constant pressure. In U.S. Pat. No.5,660,188 the two legs of a clip must also be installed in pre-drilledholes. The clip has a bridge of two side-by-side crimpable elements, andthe jaws of a crimping tool must be used on the embedded clip todeformingly spread apart these elements, causing the legs to draw toeach other. The foregoing techniques involving crimpable clips allappear to be imprecise in setting up suitable compressive' forces,require hole drilling and related problems, and do not lend themselvesto minimizing the size of the surgical opening.

In view of the limitations of the afore-mentioned methods, stapling hasbeen looked to as a potentially quick and effective way for fasteningbone segments, and as a way to produce compression. Thus in U.S. Pat.Nos. 5,053,038 and 5,662,655 “compression” staples are applied to thebone by a powered stapler. These staples have legs shaped with beveledends and/or have divergent legs that will be forced apart from eachother during implantation, which flexes springy upper parts of the legsthereby tending to set up compression. Unfortunately there is concernfor trauma to the bone due to driving of the compound-shaped legs intothe bone mass, and there is little apparent precision in establishingthe desired compressive forces.

In view of the foregoing it is a general object of the present inventionto provide an improved method and for interosseous fastening.

A more particular object is to provide quick and simple, yet effectivemethod for fastening bone segments with compressive force betweenopposing bone ends.

Another object to provide such a method that minimizes the size of therequired surgical opening and associated trauma.

A further object to provide a method of bone stapling that minimizestrauma to the bone tissue during implantation of the staple legs.

Yet another object is to provide a method for stapling that maximizesthe capability of establishing a dynamic compression level that isoptimal for enhanced osseous healing.

A still further object is to provide simple, effective bone fixationtechnique that is relatively easy to learn and practice.

Another object is to provide for compression fixation in applicationswhere other techniques would not work or would not deliver compression.For example, conventional fastening techniques for handling a “Jones”fracture, i.e. one that is transverse to the longitudinal extent of thebone segment, is difficult to address using conventional fasteningtechniques, however the present invention is particularly suitable toprovide fastening for such fractures.

Still another object is to provide stapling apparatus and method inwhich there is enhanced selection capability regarding the level of thecompressive forces to be imparted.

There are a number of advantages in exterior bone fixation techniques,where surgical incisions are not required and fasteners are appliedthrough the skin; and thus it is yet another object of the invention toprovide a bone stapling method that lends itself well to exterior bonefixation.

These and other objects of the present invention are achievable by wayof the present invention of a bone stapling method and apparatus thatuses a generally U-shaped staple having pair of spaced apart legs withsharp free ends and proximal ends interconnected by bridge that has atleast one resilient curved portion, whereby spreading apart of theparallel legs lessens the curvature of the curved portions which bringsthe staple to a tensioned configuration in which one leg is resilientlyurged towards the other. In a preferred embodiment it is seen that thebridge portion comprises a single bowed spring element, the curvature ofwhich lies in a plane normal to the axes of the staple legs.

The novel fastening method involves first positioning the fractured endsof a first and a second bone segment in proximate, face-to-facerelationship. The next step involves spreading apart the staple legs bya certain amount and holding the staple in the resultant tensionedconfiguration. The extent to which the staple legs are separated can bevaried in one preferred embodiment of the invention, the inducedcompressive forces between the legs being proportional to the amount ofdisplacement of the legs as the bowed portion is moved through range ofmotion in which elastic behavior is exhibited. In this regard it shouldbe evident that herein lies one of the advantages of the presentinvention, i.e. the capability of selecting the optimal compressiveforce for an application by spreading apart the staple legs by apredetermined amount.

Next, as the staple is held in its tensioned configuration, it ispositioned with it sharp ends forward and aligned respectively withsurfaces of one bone segments and the other. Finally the positionedstaple, while maintained in its tensioned configuration, is driven intothe bone by percussive force, such quick application being provided by aconventional air-powered striker of a stapler according to the presentinvention, or by a manually stuck staple applicator according to theinvention. The embedded staple legs will cause the opposing bone facesto be pressed into each other with a predetermined amount of force.

Such stapling method lends itself advantageously to a staple with arelatively narrow profile, wherein apparatus according to the presentinvention include a staple applicator having within its housing meansfor supporting the staple and guiding its movement with legs pointedends forwardly disposed, and adapted to receive the staple in itsinitial un-tensioned configuration engaging its legs and spreading themapart by certain amount and holding the staple in its tensionedconfiguration adjacent the front end of the housing, for ejectiontherefrom. One embodiment, of several, uses opposing first and secondgrooves for engaging the staple legs and means for adjustably moving onegroove from the other. Another embodiment employs grooves that divergeto spread the staple legs as a staple is advanced there-along. Ejectionmeans mounted for longitudinal movement in the housing has a front endadapted to strike the rear of the tensioned staple with percussive forcewhich is provided by air power or electrical power in preferredembodiments.

The invention also includes a staple applicator that is adapted forbeing manually driven.

Another related bone stapling method for compressively securingadjoining bone segments uses a resilient metallic staple that has legswith an initial convergent configuration with respect to each other, andthe legs are resiliently extendible into parallel relationship, in whichconfiguration a predetermined amount of spring force will urge the legstowards their initial convergent orientation. This method includesholding the normally convergent staple in its legs-parallelconfiguration, positioning the so-tensioned staple with its sharp endsaligned respectively with adjacent bone surfaces; and then driving andembedding the legs of the tensioned staple in the bone segments andreleasing the embedded staple, whereby the bone segments are joined, andopposing surfaces of the bone segments are caused to be pressed intoengagement with each other with a certain amount of compressive force.

An applicator or tool for such a staple includes staple-engaging meanson the front end of the applicator body. Opposing jaws support thestaple in a pointed-ends forward position against lateral and rearwardmovement, and engage inside surfaces of the convergent legs, the jawsbeing adapted for adjustable movement apart to cause the legs to rotateto a generally parallel orientation. Thus supported on the front end ofthe tool, the staple can be aligned with the bone segments, and the rearend of the tool stuck with a percussive force to cause the staple legsto be embedded into the bone segments.

Another applicator according to the present invention has atrigger-controlled air-powered staple-driving mechanism, and has astaple feeding mechanism including ramp means that is shaped to receiveand support a staple in its initial configuration on one end of saidramp means, the configuration of the ramp means gradually changing to ashape that will hold the staple with its legs generally parallel witheach other. Thus the staple can be slidably pushed along the ramp meansin a lateral direction, i.e. normal to the plane in which the staplelegs and bridge portion lie, to bring it to a terminal position alongthe ramp means, in which position the rear of the tensioned staple canbe struck by the front end of a powered striker.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is perspective view of a preferred embodiment of a compressionstaple according to the present invention;

FIG. 2 is top plan view of the embodiment of the staple of FIG. 1;

FIG. 3 is a rear end elevational view of the staple of FIG. 1;

FIG. 4 is a perspective view of variant of a staple according to thepresent invention;

FIG. 5 is an elevational view of staple applicator according to thepresent invention, with parts broken away for the sake of clarity;

FIG. 6 is a partial, perspective enlarged view of the front end of thestaple applicator of FIG. 5;

FIG. 7 is a sectional view taken long the line 7-7 of FIG. 6;

FIG. 8 is sectional view taken long the line 8-8 of FIG. 6;

FIG. 9 is an enlarged, partial perspective view of the front portion ofa variant of a staple applicator according to the present invention;

FIG. 10 is an enlarged, partial perspective view of the front portion ofanother variant of a staple applicator according to the presentinvention;

FIG. 11 is a top plan view of a manually powered stapler according tothe present invention;

FIG. 12 is a partial, enlarged perspective view of the front portion ofthe staple applicator of FIG. 11;

FIG. 13 is a sectional view taken along the line 13-13 of FIG. 12;

FIG. 14 is a perspective view of another variant of a compressive stapleaccording to the present invention, wherein the staple legs have aconvergent orientation with respect to each other;

FIG. 15 is a side elevational view of the staple of FIG. 14;

FIG. 16 is a top plan view of a staple applicator according to thepresent invention;

FIG. 17 is an enlarged, partial perspective view of the front end of theapplicator of FIG. 16;

FIG. 18 is an enlarged partial, side elevational, partially sectionalview illustrating the mounting of a staple on the front end of thestaple applicator of FIG. 16;

FIG. 19 is a view similar to FIG. 18 showing a staple supported withlegs parallel;

FIG. 20 is a perspective view of a convergent-legged staple that isadapted to be fed to a powered staple applicator;

FIG. 21 is a rear elevational view of the staple of FIG. 20;

FIG. 22 is a side elevational view of another powered applicatoraccording to the invention;

FIG. 23 is a perspective illustration showing means for feeding staplesto the staple-driving means of the powered staple applicator shown inFIG. 22;

FIG. 24 is a partial, enlarged , partial sectional side view ofstaple-delivering ramp member of the applicator shown in FIG. 22;

FIG. 25 is a schematic illustration of the staple-striking region of thestaple feeding means of FIG. 23;

FIG. 26 is a perspective view of another variant of another compressionstaple similar to the staple of FIG. 1, and adapted for use with astaple-feeding magazine or cartridge;

FIG. 27 is a front end elevational view of the staple of FIG. 26; and

FIG. 28 is a partial sectional perspective view, with parts broken awayfor the sake of clarity, illustrating a magazine or cartridge forfeeding the staple of FIG. 26 to a powered staple applicator.

DETAILED DESCRIPTION OF THE INVENTION

Referring now the drawings, FIGS. 1-3 show that a preferred embodimentof a compression staple 11 according to the present invention has a pairof legs 13 with sharp front ends 15 and a bridge 17 that interconnectsthe rear end, portions of legs 13. Staple 11 is fabricated of a surgicalgrade, bio-compatible metal, such as stainless steel, titanium alloy orother suitable alloy. Bridge 17 functions not only to hold legs 13 inapproximate parallel relationship, but is selected to act as a spring bythe flexing of its bow when the legs are spread apart as illustrated bythe broken line image of FIGS. 2 and 3. This imparts an inward reactingforce between the legs proportional to the degree of their displacement.It will be appreciated that the dimensions, gauge and curvature ofbridge 17 are selected such that it can be flexed to a tensioned statethat will deliver the compression requirements of the bone fixation towhich staple 11 is to be applied.

It is preferred that the opposing inside surfaces of legs 13 areprovided with serrations or barbs 19. In this regard it is noted that,inasmuch as the insides of legs 13 will be pressed against bone masswhen they are embedded in a manner to be described, the size of suchserrations or barbs can be advantageously minimized, which minimizestrauma to the bone tissue during their implantation.

It will be evident that there can be several variations of compressionstaples according to the principles of the invention. For example,staple legs can have various cross sectional configurations, includingdiamond-shaped, square, triangular and rectangular. FIG. 4 shows avariant 23 of a staple according to the present invention, having legs25. It is formed from metal rod having suitable strength and springproperties. It is also contemplated under the invention that thecurvature of the bridge can take other forms than the single bow shown,and would include, among others a generally V-shape and a shape withdouble 90 degree bends.

FIG. 5 shows an air-powered staple applicator 29 for applying staple 11,and it includes main body 31, a conventional air piston assembly 33within body 31, air supply line 35 and a pistol grip and triggerassembly 37 for holding the stapler and for controlling the air-poweredoperation of the staple head 41, to be described hereinafter.

As FIG. 6 illustrates, the staple head 41 features an adjustable staplemount 43 that includes lower head 45 which is a forward extension ofbody 31, and upper head 47. A pair of parallel guide rods 51, affixed tolower head 45 and extending upwardly therefrom, slidably engage twinbores 53 in the upper head 47 so as to guide the upper head in verticalmotion relative to the lower head 45. A screw jack assembly drives theupper head and includes thrust screw 55 that engages the threaded bore57 in lower head 45. FIG. 7 best illustrates the screw jack assembly andshows turn knob 59 that has a socket for receiving a tool such as anAllen wrench for rotating the knob 59. FIGS. 6 and 7 also show alongitudinally extending groove 65 on the lower head 45 and acorresponding parallel groove 63 on the movable upper head 47, thesegrooves being shaped to cradle the opposing sides of staple legs 13, andthe knob can be operated to set the spacing between grooves to allowstaple 11, in its initial un-tensioned configuration, to be mountedthereon as illustrated.

In a preferred embodiment, vertically extending gradations are providedat 67 on a forward surface of body 31, adjacent the movable rear end ofupper head 45, so as to gauge the displacement of the staple legs whenthe invention is operated in a manner to be described below.

As FIGS. 6 and 7 and 8 also show, staple applicator 29 includesmechanism for driving a staple forwardly from the staple head 41, andincludes longitudinally extending striker member 69 that is slidablymounted to grooves 71 and 73 for longitudinal movement, and the rearportion (not shown), is connected to the air piston assembly , andspring means (not shown) will hold the striker in an initial rearwardposition as illustrated in FIG. 6. Striker member 69 has front surface75 that is adapted, as best shown in FIG. 7, to impact the rear legs ofthe staple bridge 17 when the striker member 69 is propelled to itsforward position shown by the phantom lines in FIG. 6.

In the operation of staple applicator 29 for osteosynthesis, a staple 11is mounted to the staple mount 43 which is operated to bring the stapleto the desired tensioned configuration. Then bone segments are broughttogether by manual or mechanical manipulation as close as possible andaligned with each other. The stapler head 41 can then be positioned withits legs straddling the fracture line, and sharp ends 15 adjacent thesurfaces of the bone segments. The stapler trigger can then be operatedto cause the striker to drive the legs of the tensioned staple into thebone segments.

There is a variant of a staple applicator according to the inventionthat is identical to the embodiment of FIGS. 6 and 7, except that it hasa striker member 69 a is designed to engage the rear ends of staple legs13 instead of the rear edge of the staple bridge 17. Thus the sectionalview of FIG. 9 shows ends 79 and 80 that are adapted to strikerespectively the upper and lower rear ends of staple legs 13, of astaple 11 supported in tensioned configuration. It is contemplated underthe invention that ‘strikers like striker 69 a, with differently spacedends 79 and 80 can be provided so that different sized staples can beaccommodated.

FIG. 10 shows the forward portion 81 of another variant of a powerstapler applicator according to the present invention, having a mainbody 82, an upper staple guide 83 and lower staple guide 85. Opposingforward portions 87 of the guides are separated by a distance allowingit to hold staple 11 in tensioned configuration, and the rearwardportions 89 will hold the staple in its initial configuration. Theopen-sided portions 91 allow a staple to be loaded by hand unto thestaple guides. When the staple is pushed forwardly by hand from portion89 to portion 87, the divergent portions 93 will cause the spreadingapart of the staple legs, and thus a tensioned staple is positioned forejection.

A striker member 95 has upper and lower edges 97 and 99 slidably engagedin slots 101 and 103 so as to mount the striker member for longitudinalmovement. The striker front ends 105 and 107 will align with and abutthe rear ends of a tensioned staple.

FIGS. 11, 12 and 13 show a variant 113 of the invention, wherebypercussive force is delivered by hand using a suitable mallet. Here thebody 115 has a rear portion 117 designed for being struck by a mallet,and staple holder 119 at its front end. FIGS. 12 and 13 show how theholder 119 includes lower portion 121 that has staple leg-receivinggroove 129, and an adjustable upper part 135 with groove 137. FIG. 12best shows how a dove-tail portion 141 of part 135 fits in acomplementary slot for guiding vertical movement of part 135. Frontsurfaces 145 and 147 respectively of parts 121 and 135 are adapted toabut the rear ends of a staple mounted in grooves 137 and 129. A screw153 for driving the part 135 has threads 157 that engage a threaded bore159 in the movable part 135, and the knob 163 can be engaged by asuitable tool to rotate the screw 153.

In using tool 113 the sharp ends of a tensioned staple 11 canadvantageously be precisely positioned on the target spots on the bonesegments, then the tool end 117 struck with a mallet to implant thestaple.

Referring now to FIGS. 14 and 15 there is shown in FIG. 14 anothercompressive staple 161 according to the invention that is fabricated ofa suitable resilient metal, and features legs 163 and 165 that convergewith respect to each other, and interconnect by a bridge 167. Staple 161can also be made of a suitable resilient non-metallic bio-absorbablematerial.

FIG. 15 best shows how legs 163 and 165 each converge at a pre-selectedangle φ with respect to parallel positions that the legs can beresiliently urged in a manner to be described hereinafter. It should beapparent that the material properties of the selected resilientmaterial, the degree of convergence, and the dimensions and form of thestaple will be selected by those with ordinary skill in the pertinentart so as to establish a certain force by which the parallel legs areurged to their convergent positions.

FIG. 16 shows one preferred embodiment of a bone-staple applicator 171having a main body 173 with a rear end 175 adapted for being impacted bya force delivering instrument like a mallet. The front end 177 isdesigned to mount a staple 161 in its initial configuration and thenmove it to, and hold it in, a configuration where its legs are parallel.Thus it is seen in FIG. 17 that front end 177 has an upper jaw 181 thatcan be adjustably spaced from to a lower jaw 183 using drive-screwmechanism similar to that used for the screw-driven spreadable parts 135and 121 previously described above and shown in FIGS. 12 and 13. FIG. 17shows how the upper jaw 181, and lower jaw 183 are shaped to mount astaple 161, the slots 187 and 189 in the respective jaws being sized toreceive the staple bridge 167. A recessed portion 191 in the top of thejaw 181 is for supporting and stabilizing rearward portions of the upperstaple leg 163, and there is a similarly recessed portion on theunder-surface of the lower jaw 183 (not shown) for supporting therearward part 196 of lower staple leg 165. The recessed portion 191 hasa shelf 193 for engaging lower surfaces of leg 163, and opposing edges195 can hold the staple against lateral movement while the ledge 197 isadapted to abut the rear edge of the staple leg.

FIG. 18 best shows how an untensioned staple 161 is first mounted withinthe grasp of the opposing recessed portions of the jaws 181 and 183, andit is noted how surfaces 193 and 194 engage inner surfaces 211 and 213of opposing legs 163 and 165. It should be appreciated how the screwmechanism 217 can be operated to move apart the opposing jaws, causingthe opposing legs to be pushed into parallel relationship, asillustrated in FIG. 19. When a staple 161 is thusly mounted on theapplicator tool 171, it can be used much the same as the previouslydescribed device 113, to apply a tensioned staple 161 to adjoining bonesegments. Note that the jaw surfaces 193 and 194 can be appropriatelysloped to ensure that the legs will be pushed into parallelism.

FIGS. 20 and 21 show another embodiment of a compression stapleaccording to the present invention, i.e. the staple 261 which isparticularly adapted for application by a powered applicator, forexample an electrically powered or an air-powered staple applicator suchas applicator 271 shown in FIG. 22, to be described. Like the previouslydescribed staple 161, the staple 261 is fabricated of a suitableresilient metal using conventional metal-working techniques. The staplelegs 263 and 265 extend from the bridge portion 267 and converge at apredetermined angle. It is noted how legs 263 and 265 are wider than thebridge portion 267. The inside surfaces of the staple bridge and legsare adapted to slidably engage staple-feeding ramp structure, to bedescribed. Furthermore, FIG. 21 best shows how this staple structureprovides to one side of the bridge 267, opposing inside surfaces 270 and274 respectively of legs 263 and 265, which can be advantageouslyengaged for slidable forward movement of the staple along parallel guidesurfaces in the powered staple applicator 271, in a manner to bedescribed.

The trigger-controlled applicator 271, shown in FIG. 22, except for itsforward end, is similar to the above-described applicator 29, andincludes a piston assembly 275. FIG. 23 illustrates how at the forwardend of the applicator 271, there is mounted a staple feeder 273 designedto supply and position staples for engagement by the front end 279 of astriker 281 that is connected to the piston assembly 275.

FIG. 23 shows that the feeder 273 includes a housing 285 that isattached to a sidewall of the applicator and which supports a rampmember 287 that has a distal end 289 that is shaped to receive staples261. The walls 291, 292 and 293 are shaped so as to be slidably embracedby a number of staples 261 in their relaxed, legs-convergentconfigurations. FIG. 24 also illustrates the ramp member 287 and showshow the ramp walls 291 and 292 vary from a convergent orientation at oneramp end to a generally parallel one at the opposite ramp end 294. FIG.23 also illustrates that within the feeder housing 285 there is aspring-powered pusher 295, connected to a suitable conventional spring(not shown) for urging the pusher 295 against the rear side edges of astaple 261 mounted on the ramp member 287. Thus it can be appreciatedhow a staple 261, or several side-by-side staples 261, can be slidablypushed towards the end 294 of the ramp member.

The enlarged view of FIG. 25 shows how the innermost end of the rampmember 287 has an end 299 that is spaced from a guiding surface 301 ofapplicator wall 304. Surfaces 301 and the opposing upper and lowersurfaces 303 and 305 form a channel as FIG. 24 shows, for receiving thestriker 281. FIG. 25 shows in broken lines a tensioned staple 261 inposition for being driven by the striker 281. Note that the bridgemember 267 is spaced within the above-mentioned channel, clear of theend of the ramp member 287, the staple being supported by virtue of thestaple leg surfaces 270 and 274 (FIG. 21) engaging the ramp member. Thusthe striker front end 279 is aligned with the rear end of staple bridgeportion 267.

In operation of applicator 271 it is supported with its front end inclose proximity to the relevant bone segments, and with the pointed endsof the staple appropriately aligned therewith. Pulling the trigger willcause the striker end 279 to impact the staple bridge and propel thestaple forwardly as the staple legs are held generally parallel bysliding engagement with the generally parallel surfaces of the rampmember 287 during ejection.

The striker will have a stroke sufficient to cause the legs, in theirparallel configuration, to be embedded in the bone tissue. The strikerwill return to its initial position rearward of the ramp member. Thenspring force will cause another staple to be positioned in the ejectionchannel.

Although FIGS. 22 and 23 show the feeder 273 connected adjacent thefront end 260 of the applicator, it should be appreciated that in somecases it is desirable that the feeder 273 attaches to the applicator 271at a location spaced a greater distance to the rear of the front 260. Insuch cases the ramp walls 291 and 292 in the region of wall 301 areelongated forwardly as necessary to provide guide surfaces for thestaple, and the stroke of the striker 281 is increased accordingly.

FIGS. 26 and 27 illustrate yet another variant 361 of the compressionstaple 11 described above (FIG. 1), and has generally parallel legs 363and 365 and resilient bridge 367. This configuration provides opposingsurfaces 370 and 374, best shown in FIG. 27, that are adapted to engageparallel guide surfaces when the staple 361 is propelled from a poweredstaple applicator 371; to be described. In FIG. 27 the tensionedconfiguration of staple 361 in shown in broken lines.

FIG. 28 shows a feeder 373 which is constructed similarly to theabove-described feeder 273, except that the ramp member 387 is adaptedto handle the staple 361. Thus the ramp walls 391 and 392 provideparallel surfaces for engaging inside surfaces of the staple legs andthe wall 393 slidably abuts the wall 393.

The distal end of the ramp 387 receives staples 361 in their untensionedcondition, and the walls 391 and 392 gradually diverge from each othersuch that at the other end 395 of the ramp, a staple 361 will besupported in a legs-parallel tensioned configuration. A spring-poweredpusher 399 is adapted to urge a number of nested staples 361 towards theend 395 of the ramp.

The ramp end 395 is spaced a predetermined distance from the guidesurface 401 and provides surfaces that engage the opposing surfaces 370and 374 of staple 361. Thus the rear of a tensioned staple can be struckby the striker 397 and ejected from the applicator.

While particular embodiments of the invention have been described, itshould be understood that the invention is not limited thereto, andincludes other variants and modifications that will readily occur tothose persons of ordinary skill in the art, given the benefit of thisdisclosure. Thus it is intended that the invention be given its fullscope and breath as defined in the claims which follow.

1. A bone staple applicator for driving one or more bone staples intobone segments to secure the bone segments across a fracture site, eachbone staple comprising two legs and a substantially flat bridge portioncoupling the two legs to one another, the two legs and substantiallyflat bridge portion each having inside surfaces, the bone stapleapplicator comprising: an elongate main body having a proximal end, adistal end, and a longitudinal axis extending therethrough; a bonestaple feeder having a proximal end, a distal end coupled to the distalend of the elongate main body to define a bone staple receiving channel,and a longitudinal axis extending between said proximal and distal endsthat is substantially perpendicular to the longitudinal axis of theelongate main body, the bone staple feeder being adapted to feed a bonestaple into the bone staple receiving channel, wherein the bone staplefeeder comprises an elongate ramp member and a pusher slidably coupledto the elongate ramp member, the elongate ramp member being adapted toslideably engage the substantially flat inside surfaces of the two legsand substantially flat bridge portion of each bone staple, the rampmember further being adapted to accommodate a plurality of bone staplesin a side-by-side configuration wherein the two legs of a first bonestaple are adjacent to the two legs of an adjacent second bone staple;and a staple striker slidably coupled to the elongate main body andadapted to strike the substantially flat bridge portion of the bonestaple placed in the bone staple receiving channel with sufficientpercussive force to drive the legs of said bone staple into bone.
 2. Thebone staple applicator of claim 1, wherein each bone staple does not anyprotrusions extending proximally from the substantially flat bridgeportion.
 3. The bone staple applicator of claim 1, wherein each bonestaple has a relaxed configuration wherein the two legs of the bonestaple converge toward one another and a tensioned configuration whereinthe two legs of the bone staple are substantially parallel.
 4. The bonestaple applicator of claim 3, wherein the elongate ramp member has aproximal end and a distal end, and wherein the elongate ramp member isshaped to urge a bone staple from the relaxed configuration to thetensioned configuration as the pusher advances the bone staple from theproximal end of the elongate ramp member to the distal end of theelongate ramp member.
 5. The bone staple applicator of claim 4, whereinthe elongate ramp member comprises side surfaces adapted to face theinside surfaces of the two legs of a bone staple.
 6. The bone stapleapplicator of claim 5, wherein the side surfaces have a convergentorientation at the proximal end of the elongate ramp member.
 7. The bonestaple applicator of claim 5, wherein the side surfaces have asubstantially parallel orientation at the distal end of the elongateramp member.
 8. The bone staple applicator of claim 3, wherein theelongate ramp member has a proximal end and a distal end, wherein thedistal end of the elongate ramp member is adapted to maintain a bonestaple fed into the bone staple receiving channel in the tensionedconfiguration.
 9. The bone staple applicator of claim 1, wherein thepusher is adapted to advance a second bone staple into the bone staplereceiving channel after a first bone staple has been driven out of thebone staple receiving channel by the staple striker.
 10. The bone stapleapplicator of claim 8, wherein the bone staple feeder comprises a springcoupled to the pusher to advance the pusher.
 11. The bone stapleapplicator of claim 1, wherein the staple striker is adapted to drivethe legs of a bone staple into bone such that the legs are maintained ina substantially parallel orientation in the bone.